Swallow-induced esophageal shortening in patients without hiatal hernia is associated with gastroesophageal reflux

Longitudinal esophageal body shortening with swallow-induced peristalsis has been reported in healthy individuals. Esophageal shortening is immediately followed by esophageal re-elongation, and the lower esophageal sphincter (LES) returns to the baseline position. High-resolution manometry (HRM) allows for objective assessment of extent of shortening and duration of shortening. In patients without hiatal hernia at rest, swallow-induced esophageal shortening can lead to transient hiatal hernia (tHH) which at times may persist after the completion of swallow. This manometric finding has not been investigated in the literature, but a question arises whether this swallow-induced transient herniation can effect on the likelihood of gastroesophageal reflux. This study aims to assess the relationship between gastroesophageal reflux and the subtypes of swallow-induced esophageal shortening, i.e. tHHand non-tHH, in patients without hiatal hernia at rest. After Institutional Review Board (IRB) approval, we queried a prospectively maintained database to identify patients who underwent HRM evaluation and 24-hour pH study between January to December 2015. Patients with type-I esophagogastric junction (EGJ) morphology (i.e. no hiatal hernia) according to the Chicago classification v3.0 were included. The patterns of the esophageal shortening with swallows were divided into two subtypes, i.e. tHH and non-tHH. tHH was defined as an EGJ double high-pressure zones (>= 1 cm) at the second inspiration after the termination of swallow-induced esophageal body contraction. The number of episodes of tHH was counted per 10 swallows and tHH size was measured for each patient. In total, 41 patients with EGJ morphology Type-I met the inclusion criteria. The mean age was 47.2 years, 35 patients (85.4%) were women, and the mean body mass index was 33.9 kg/m(2). The mean number of tHH episodes was 3 out of 10 swallows; mean maximal tHH size was 1.3 cm. Patients who had tHH in >= 3 out of 10 swallows (n = 16; 39.0%) were more likely to have abnormal DeMeester scores than patients with < 3 swallows (56% vs. 28%; P = 0.070). Patients with maximal tHH >= 2 cm in at least 1 swallow (n = 17; 41.5%) were more likely to experience pathological reflux than patients with maximal tHH < 2 cm (59% vs. 25%; P = 0.029). In conclusion, we showed that, in a subset of patients with Type-I EGJ morphology, swallowing induced transient EGJ double high-pressure zones (>= 1 cm) after peristalsis. We have named this new manometric finding the swallow-induced tHH. A high prevalence of pathological reflux disease was observed in patients with maximal tHH >= 2 cm. The degree of swallow-induced tHH could be an early indicator of lower esophageal sphincter dysfunction in patients without manometric hiatal hernia.